meson: Install libgnomekbd{,ui}.so.8
Previously, the meson build system would install:
- libgnomekbd.so.3.28.0 with symlinks from
- libgnomekbd.so.8.0.0
- libgnomekbd.so
This didn't match the autotools build system, which installed:
- libgnomekbd.so.8.0.0 with symlinks from
- libgnomekbd.so.8
- libgnomekbd.so
The ABI didn't change between v3.26.1 (which only had autotools) and v3.28.0, so I don't think we should install .so.3.28.0 shared objects.
This change makes meson install the same shared objects and symlinks as autotools.